1. Field of the invention
The present invention relates to an inner cutter for a dry shaver, and more particularly a process of forming the inner cutter having a plurality of archlike blades which are supported only with a plastic frame.
2. Description of the Prior Art
As described in U.S. Pat. No.3,858,461, the prior art method of forming a landless inner cutter for an electric shaver has included the steps of removing material from a strip of sheet metal to provide the strip with a first archlike edge which has a rise and a span, cutting a second archlike edge in the strip which is longitudinally displaced such that the span of the second edge intersects with the rise of the first edge, bending the resulting arch-shaped blade section between the archlike edges out of and normal to the plane of the strip, so as to provide a normally disposed, arch-shaped blade section and to expose another first archlike edge in the plane of the strip, and repeating the cutting and bending steps, as necessary, to provide a plurality of equidistantly-spaced, normally disposed, arch-shaped blade sections in the strip. Each of the arch-shaped blade sections is supported only at the spaced side portions of the blade section relative to the strip, so that all of the blade sections have an unitary structure with the strip. Therefore, the prior art provides a process for readily forming closely spaced blade sections of the inner cutter in a strip of the sheet metal without forming lands between the blade sections. However, as the spaced side portions do not have enough strength to tightly support the blade sections, the inner cutter does not have good shearing performance when it is reciprocated relative to an outer cutter for shearing hairs. On the other hand, for improving the strength, it is considered that the spaced side portions of the blade sections are reinforced with a plastic. However, a large amount of shrinkage of the plastic occurs after the spaced side portions have been reinforced by the plastic. As the individual blade sections are connected with the metal sheet molded in the plastic frame, a total shrinkage stress of the plastic generated between the plastic frame and the metallic blade sections is very large, so that some cracks are generated in the plastic frame. As a consequence, the strength is not improved.